Ultrasensitive determination of aflatoxin B1 by flow injection chemiluminescence immunoassay based on hemin-integrated Tb-MOF(Fe) nanozyme.

Nanozymes are promising alternatives to natural enzymes in biosensing applications. To address the critical need for sensitive detection of the food contaminant aflatoxin B1 (AFB1), this study developed a chemiluminescence immunosensor utilizing a novel Tb-MOF(Fe) nanozyme. The Tb3+-based metal-organic framework (MOF) was synthesized via a facile one-pot method employing 4,4'-oxybisbenzoic acid (OBBA) and catalytic hemin as ligands. Encapsulation of hemin within the MOF matrix markedly enhanced the stability and peroxidase-like activity of the material. Featuring an abundant porous structure and numerous active sites, the resulting Tb-MOF(Fe) substantially enhanced the chemiluminescence (CL) intensity of the luminol-H₂O₂ system. These properties enable the construction of multifunctional immunoprobes that integrate catalysis, luminescence enhancement and antibody immobilization. Implementing Tb-MOF(Fe) within a flow-injection chemiluminescence immunoassay (FI-CLIA) facilitated ultrasensitive detection of AFB1. The assay demonstrated a broad linear range (0.004-1000 ng mL-1), ultralow limit of detection (LOD) (1.3 pg mL-1, S/N = 3), and reliable spiked recovery rates (86.92-118.87%) in complex corn and wheat matrices, confirming its practical applicability in complex matrices. This study provides a highly sensitive strategy for AFB1 detection and advances the application of nanozymes in food safety.